H- FORMATION IN THE SCATTERING OF HYDROGEN-IONS ON AN AL SURFACE

We present results of an experimental and theoretical investigation of H- formation in collisions of 1-4 keV positive and negative hydrogen ions with clean Al surfaces. The scattered ion fractions were investig ated in a large angular range extending from 2 to 40 degrees with resp ect to the surface plane. This allowed us to investigate the character istics of the resonant charge transfer process in a wide range of coll ision velocities normal to the surface, allowing us in particular to r each the domain where small atom-surface distances play an important r ole. Results of theoretical calculations could thus be tested in a mor e stringent manner than in previous high grazing-incidence experiments of Wyputta et al.